Sealing element and method for producing a sealing element

ABSTRACT

In order to provide a sealing element, in particular for use as a rod seal, piston seal and/or shaft seal, which ensures a reliable seal and which can be produced easily and economically, it is proposed that the sealing element includes a main body formed from a thermoplastic material, wherein the main body has obtained at least part of its final outer shape in a high-pressure process and/or in a high-temperature process.

RELATED APPLICATION

This application is a continuation of U.S. application Ser. No. 15/606,238 filed on May 26, 2017, which is a continuation of international application No. PCT/EP2015/077942 filed on Nov. 27, 2015, and claims the benefit of German application No. 10 2014 224 378.5 filed on Nov. 28, 2014 which are incorporated herein by reference in their entirety and for all purposes.

FIELD OF DISCLOSURE

The present invention relates to a sealing element, in particular for use as a rod seal, piston seal and/or shaft seal.

Such a sealing element is known by way of example from DE 10 2012 112 594 A1.

SUMMARY OF THE INVENTION

The object of the present invention is to provide a sealing element which ensures a reliable seal and which can be produced easily and economically.

This object is achieved in accordance with the invention by a sealing element which comprises a main body made of a thermoplastic material, wherein the main body has obtained at least part of its final outer shape in a high-pressure process and/or in a high-temperature process.

Alternatively, it can be provided that the sealing element comprises a main body made of a thermoplastic material, wherein the main body has obtained only part of its final outer shape in a high-pressure process and/or in a high-temperature process.

The sealing element, in particular the main body of the sealing element, is preferably produced with near net shape.

A final outer shape is in particular the shape that the main body has in the state of use of the sealing element or in the state ready for use.

A final outer shape is also in particular a shape in which there is no further processing, for example no re-shaping of the surface, before the main body is used as intended as part of the sealing element.

It can be advantageous if the main body, at least in part or only in part, has a surface finish which comprises a body shaped and/or completed in a high-pressure process and/or in a high-temperature process.

It can be advantageous if the main body, at least in part or only in part, has a surface finish which comprises a body shaped and/or completed in an injection molding process.

In one embodiment of the invention it can be provided that the main body is substantially ring-shaped.

The main body preferably comprises one or more radially inner sealing portions and also one or more radially outer sealing portions with respect to the ring shape.

For simplification, the sealing portions will be discussed hereinafter in the singular. However, a plurality of sealing portions having one or more of the mentioned features can of course also be provided at all times.

The main body can be circular ring-shaped by way of example.

A radially inner sealing portion serves preferably to provide a dynamic seal on a movable element, in particular a piston, a rod, or a shaft.

A radially outer sealing portion serves preferably to provide a static seal on a housing of a sealing device.

It can be favorable if the radially inner sealing portion and/or the radially outer sealing portion have/has obtained their/its final outer shape in the high-pressure process and/or in the high-temperature process.

It can be provided here that only the radially inner sealing portion or only the radially outer sealing portion or both the radially inner sealing portion and the radially outer sealing portion has/have obtained its/their final outer shape in the high-pressure process and/or in the high-temperature process.

Alternatively or additionally, it can be provided that a radially inner sealing portion and/or a radially outer sealing portion have/has obtained the corresponding final outer shape by means of a finishing operation, for example a machining operation.

In a further development of the invention it can be provided that the main body comprises two ends which are opposite one another with respect to an axial direction and which in particular in the state of use of the sealing element come into contact with fluids to be separated from one another.

Only one of the ends or both ends has/have obtained the final outer shape preferably in the high-pressure process and/or in the high-temperature process.

Alternatively or additionally, it can be provided that only one of the ends or both ends has/have obtained the final outer shape by means of a finishing operation, for example a machining operation.

One end or both ends is/are preferably provided with one or more spring element receptacles for receiving one or more spring elements.

It can be favorable if the main body comprises a thermoplastic material which in particular is injection-moldable, or is formed from a thermoplastic material which in particular is injection-moldable.

The thermoplastic material can be in particular a fluoro-thermoplastic material, for example a fully fluorinated thermoplastic material.

The main body is preferably an injection-molded component, in particular a plastics injection-molded component.

The sealing element can be a spring-assisted grooved ring, for example.

The sealing element then preferably comprises one or more spring elements, which for example are formed from a spring steel and have a ring shape at least roughly.

Here, one or more spring elements by way of example can have a U-shaped, V-shaped or L-shaped cross-section as considered at right angles to a circumferential direction.

The present invention also relates to the use of a sealing element, in particular a sealing element according to the invention, as a rod seal, piston seal and/or shaft seal.

Here, the sealing element is preferably used in a fuel pump and/or a piston pump for sealing two media spaces.

The use according to the invention preferably has one or more of the features and/or advantages described in conjunction with the sealing element according to the invention.

The present invention also relates to a method for producing a sealing element.

In this regard, the object of the invention is to provide a method by means of which a sealing element that provides a reliable seal can be produced easily and economically.

This object is achieved in accordance with the invention by a method for producing a sealing element, wherein the method comprises the following: producing a main body of the sealing element from a thermoplastic material, wherein the main body obtains at least part of its final outer shape or only part of its final outer shape in a high-pressure process and/or in a high-temperature process.

The method according to the invention preferably has one or more of the features and/or advantages described in conjunction with the sealing element according to the invention and/or the use according to the invention.

It can be favorable if the high-pressure process comprises an embossing process, a press molding process, an injection molding process and/or a pressure diecasting process.

The main body thus obtains at least part of its final outer shape or only part of its final outer shape preferably in an embossing process, a press molding process, an injection molding process and/or a pressure diecasting process.

Alternatively or additionally, it can be provided that the high-temperature process comprises a hot embossing process, a hot press molding process, an injection molding process, a casting process, a sintering process and/or a thermoforming process.

The main body thus obtains at least part of its final outer shape or only part of its final outer shape preferably in a hot embossing process, a hot press molding process, an injection molding process, a casting process, a sintering process and/or a thermoforming process.

It can be favorable if the main body of the sealing element is subjected to a finishing operation only in part after the high-pressure process and/or the high-temperature process have/has been performed.

By way of example, a partial finishing only on one side can be provided, in particular a one-sided finishing axially and/or radially.

However, it can also be provided that the main body is subjected to a finishing operation on both sides in the axial direction and/or on both sides in the radial direction.

The main body is preferably machined.

Alternatively or additionally, it can be provided that the main body is coated for the finishing or as the finishing.

One or more sealing portions of the sealing element is/are preferably produced by a processing of the main body.

By way of example, it can be provided that one or more dynamic sealing portions of the sealing element and/or one or more static sealing portions of the sealing element have/has been produced by a processing, in particular a machining, of the main body.

One or more spring element receptacles for receiving one or more spring elements is/are preferably not subjected to a finishing operation, but instead obtains/obtain its/their final outer shape preferably in the high-pressure process and/or in the high-temperature process.

It can be particularly advantageous if the main body is produced from partially fluorinated or fully fluorinated thermoplastic material which preferably is injection-moldable.

It can be provided that the main body is formed from pure PTFE material.

The thermoplastic material (plastics material) is preferably melt-processable.

The plastics material used is preferably a TFE copolymer with a comonomer content of more than 0.5 wt. %. By means of a comonomer content of this order, the molecular weight of the polymer chains can be reduced without detriment to the mechanical strength of the material, and therefore the melt viscosity is reduced and processing by means of injection molding is made possible.

The comonomer is preferably selected from a perfluoroalkyl vinyl ether, in particular perfluoromethyl vinyl ether, hexafluoropropylene and perfluoro-(2,2-dimethyl-1,3-dioxole). Depending on the comonomer content, the fully fluorinated thermoplastic is then what is known as a melt-processable PTFE (comonomer content up to approximately 3 wt. %), a PFA (more than approximately 3 wt. % perfluoroalkyl vinyl ether as comonomer), an MFA (more than approximately 3 wt. % perfluoromethyl vinyl ether as comonomer), or an FEP (more than approximately 3 wt. % hexafluoropropylene as comonomer).

The TFE copolymer can also comprise different comonomers. It is also possible that the fully fluorinated thermoplastic comprises a mixture of different TFE copolymers.

The material of the main body can be formed in part or substantially completely from the fully fluorinated thermoplastic. Alternatively or additionally, the material can comprise one or more fillers, in particular pigments, friction-reducing additives and/or additives increasing the thermal resistance, in order to further optimize the properties of the sealing element and to adapt these to the relevant requirements.

The sealing element is suitable in particular for sealing pistons in high-pressure fuel pumps or piston pumps for brake systems (ABS, ESP, etc.).

In particular, a thermoplastic material that is resistant to high temperature and/or chemicals, in particular PEEK, PEAK, PEI, etc., and/or a compound material comprising one or more of the above-mentioned materials can also be used as thermoplastic material.

A high dimensional stability of the thermoplastic material can be attained in particular by production of the main body of the sealing element in an injection molding process so as to ultimately seal off higher pressures in particular.

The high-pressure process is in particular a high-pressure forming process.

The high-temperature process is preferably a high-temperature forming process and/or a high-temperature conversion process.

It can be provided that the high-pressure process and/or the high-temperature process are/is the only process steps or step for producing the main body.

Alternatively, further process steps can be carried out in order to produce the main body.

By way of example, in order to produce a main body of a sealing element, it can be provided that the thermoplastic material is pre-fabricated in an extrusion process, in particular a ram extrusion process, and is then brought into the final outer shape by grinding and milling, turning, or other machining operation.

It can also be provided that a main body of a sealing element is produced by carrying out the following method steps: extruding the thermoplastic material, in particular ram-extruding the thermoplastic material; grinding; machining in a turning machine; hot embossing; CNC finishing, in particular in order to produce an inner contour, for example one or more radially inner sealing portions.

In a further embodiment it can be provided that a main body of the sealing element is produced by carrying out the following method steps: pressing a blank; carrying out a sintering process; hot embossing; CNC processing, in particular in order to produce an inner contour, for example one or more radially inner sealing portions.

A main body of a sealing element can also be produced for example by carrying out the following method steps: pressing a blank; carrying out a sintering process; CNC processing of the main body, in particular in order to produce an outer contour and/or an inner contour, for example in order to produce one or more radially inner sealing portions and/or one or more radially outer sealing portions.

A main body of a sealing element can also be produced by carrying out the following method steps: granulating a starting material; using this starting material in an injection molding process in order to produce the main body; subjecting the main body to a finishing operation as appropriate, in particular CNC processing in order to produce an inner contour, for example one or more radially inner sealing portions.

A completed main body can be connected as appropriate to further components of the sealing element, or can be assembled thereon, and finally packaged.

Further preferred features and/or advantages of the invention are the subject of the following description and the representation in the drawings of exemplary embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a schematic longitudinal section through a main body of a sealing element, wherein the main body has its final outer shape only in part;

FIG. 2 shows a schematic illustration, corresponding to FIG. 1, of the main body, wherein the main body has been processed to complete an outer contour; and

FIG. 3 shows a schematic illustration, corresponding to FIG. 1, of a sealing element which comprises the completed main body and two spring elements.

In all figures, like or functionally equivalent elements are provided with the same reference signs.

DETAILED DESCRIPTION OF THE DRAWINGS

An embodiment illustrated in FIGS. 1 to 3 of a sealing element denoted as a whole by 100 is, for example, part of a high-pressure pump 102 and serves to provide a seal between two media spaces 104 in the region of a movable component 106.

The movable component 106 can be a piston of the high-pressure pump 102, for example.

The movable component 106 is in particular guided through the sealing element 100.

Here, both the movable component 106 and the sealing element 100 are preferably rotationally symmetrical about an axis of symmetry 108.

The axis of symmetry 108 is in particular oriented parallel to a longitudinal axis 110 of the movable component 106 and of the sealing element 100.

The sealing element 100 and the movable component 106 have a common axis of symmetry 108 in the assembled state.

The longitudinal axis 110 preferably defines an axial direction 112.

A direction oriented at right angles to the axial direction 112 is a radial direction 114.

The media spaces 104 are preferably separated from one another in the axial direction 112 by means of the sealing element 100.

The sealing element 100 here borders the movable component 106 in the radial direction 114 in an inwardly directed manner by means of two dynamic sealing portions 116.

The sealing element 100 borders a housing 118 of the high-pressure pump 102 in an outwardly directed manner in the radial direction 114.

The sealing element 100, in the assembled state, is fixed relative to the housing 118.

Two sealing regions 120 of the sealing element 100 associated with the two media spaces 104 thus comprise, in addition to the dynamic sealing portions 116, also two static sealing portions 122 bearing against the housing 118.

The dynamic sealing portions 116 serve to provide the dynamic seal between the sealing element 100 and the component 106 moving relative to the sealing element 100, in particular displaceable along the axial direction 112.

In order to attain an increased sealing effect, one or more spring elements 124 of the sealing element 100 can be provided.

The one or more spring elements 124 in particular can be arranged or is/are arranged in one or more spring element receptacles 126.

In particular, one or more dynamic sealing portions 116 can be pressed against the movable component 106 by means of the one or more spring elements 124.

Alternatively or additionally hereto, it can be provided that one or more static sealing portions 122 can be pressed against a housing 118 of the high-pressure pump 102 by means of the one or more spring elements 124.

Each dynamic sealing portion 116 preferably comprises one, two or more than two sealing lips 128.

Each sealing lip 128 is preferably substantially annular and substantially rotationally symmetrical about the axis of symmetry 108.

The sealing lips 128 are arranged here preferably at different spacings from a transverse central plane 130 of the sealing element 100 running at right angles to the longitudinal axis 110 of the sealing element 100.

The sealing element 100 in particular comprises a main body 132, which is formed preferably in one piece from a thermoplastic material.

The main body 132 in particular comprises one or more dynamic sealing portions 116, one or more static sealing portions 122, and one or more spring element receptacles 126.

The main body 132 by way of example can be produced as follows.

By way of example, a blank 134 of the main body 132 can be produced in an injection molding process.

The blank 134 of the main body 132 at this point has its final outer shape only in portions.

In particular, merely the spring element receptacles 126 are completed at the time of production of the blank 134.

By contrast, the sealing portions 116, 122 must be subjected to a finishing operation in order to complete the main body 132, in particular by machining, for example CNC processing.

As is clear in particular from a comparison of FIGS. 1 to 3, an outer contour can first be processed by way of example, in order to complete the radially outer static sealing portions 122. A radially inner processing can then be performed in order to complete the dynamic sealing portions 116.

Alternatively, it can be provided that the blank 134 is produced for example in an injection molding method in such a way that both the static sealing portions 122 and the spring element receptacles 126 already have the final outer shape after the execution of the injection molding process.

Merely the radially inner region then still has to be subjected to a mechanical finishing operation in order to complete the dynamic sealing portions 116.

In particular, the main body 132 and thus the entire sealing element 100 can be produced particularly efficiently and economically by a combination of production of the blank 134 in a high-pressure process and/or a high-temperature process, for example an injection molding process, on the one hand and only partial subsequent processing in order to complete the main body 132 on the other hand. 

1. A sealing element, comprising a main body formed from a thermoplastic material which has obtained only part of its final outer shape in a high-pressure process or in a high-temperature process, which is an injection molding process, wherein the main body consists of a fluoro-thermoplastic material, wherein the main body is annular and comprises two radially inner dynamic sealing portions for dynamically sealing between the sealing element and a movable component, wherein the main body further comprises one or more radially outer sealing portions,0 wherein each dynamic sealing portion comprises one, two or more than two sealing lips, wherein the dynamic sealing portions have obtained their respective final outer shape by machining, wherein the one or more radially outer sealing portions have obtained their final outer shape in the high-pressure process or in the high-temperature process, wherein the main body is an injection-molded component.
 2. The sealing element according to claim 1, wherein the main body only in part has a surface finish which comprises a body formed or completed in a high-pressure process or in a high-temperature process.
 3. The sealing element according to claim 1, wherein the main body only in part has a surface finish which comprises a body formed or completed in an injection molding process.
 4. The sealing element according to claim 1, wherein the sealing element is configured for use as a rod seal, piston seal or shaft seal, in particular in a fuel pump or a piston pump.
 5. The sealing element according to claim 1, wherein the sealing element is a spring assisted grooved ring.
 6. The sealing element according to claim 1, wherein the flouro-thermoplastic material of the main body is melt-processable.
 7. A method for producing a sealing element, comprising: producing a main body of the sealing element from a thermoplastic material, wherein the main body obtains only part of its final outer shape in a high-pressure process or in a high-temperature process, wherein the main body consists of a fluoro-thermoplastic material, wherein the main body is annular and comprises two radially inner dynamic sealing portions for dynamically sealing between the sealing element and a movable component, wherein the main body further comprises one or more radially outer sealing portions, wherein each dynamic sealing portion comprises one, two or more than two sealing lips, wherein the dynamic sealing portions obtain their respective final outer shape by machining, wherein the one or more radially outer sealing portions obtain their final outer shape in the high-pressure process or in the high-temperature process, wherein the high-pressure process or the high-temperature process is an injection molded process.
 8. The method according to claim 7, wherein the main body of the sealing element is subjected to a finishing operation only in part after the high-pressure process or the high-temperature process has been performed.
 9. The method according to claim 8, wherein the main body is coated.
 10. The method according to claim 7, wherein the main body is produced from partially fluorinated or fully fluorinated thermoplastic material which in particular is injection-moldable.
 11. The sealing element according to claim 1, wherein each of the one, two or more than two sealing lips are substantially annular.
 12. The sealing element according to claim 1, wherein an axis of symmetry is defined parallel to a longitudinal axis of the movable component and the sealing element, and wherein each of the one, two or more than two sealing lips are substantially rotationally symmetrical about the axis of symmetry.
 13. The sealing element according to claim 1, wherein each of the two radially inner dynamic sealing portions are configured to be pressed against the movable component by means of one or more spring elements.
 14. The sealing element according to claim 13, wherein the main body further comprises one or more spring element receptacles configured to receive the one or more spring elements.
 15. The sealing element according to claim 1, wherein the one, two or more than two sealing lips are arranged at different spacings from a transverse central plane of the sealing element which runs at a right angle to a longitudinal axis of the sealing element. 